As a liquid discharging device, several variations have been known. Particularly, as a discharging device that can discharge liquid having a high viscosity such as silver paste in infinitesimal quantity with high accuracy at high speed, a device which drives concentrically-arranged three members has been known (see, Patent Document 1).
The liquid discharging device according to Patent Document 1 includes; a suction-path opening/closing member that opens and closes a suction-path that suctions liquid; a discharge-outlet opening/closing member that opens and closes a discharge outlet that discharges the liquid; and a discharging member that discharges the liquid. In the liquid discharging device, the discharge-outlet opening/closing member, the discharging member and the suction-path opening/closing member are concentrically arranged in this order from inside toward outside. The liquid discharging device further includes a driving mechanism that drives each of the discharge-outlet opening/closing member, the discharging member and the suction-path opening/closing member to perform a predetermined operation.
A suctioning operation in the pump is performed in the following manner: opening the suction-path opening/closing member to move the discharging member in a direction away from the discharge outlet; and suctioning the liquid into a space formed between the discharge outlet and the discharging member. On the other hand, a discharging operation is performed in the following manner: closing the suction-path opening/closing member after the liquid is suctioned; measuring the liquid to be discharged; opening the discharge-outlet opening/closing member to move the discharging member toward the discharge outlet side; discharging the liquid using the discharging member; and lastly closing the discharge-outlet opening/closing member to complete the discharging operation.
The liquid discharging device drives the members such as the discharging member using an air cylinder. By forcefully driving each of the members, the liquid discharging device can volume metric-measure the liquid confined in the space between the members. With this arrangement, the liquid discharging device can discharge the liquid even in infinitesimal quantity with high accuracy. By reducing weight of the device, the device can be attached on a robot in a production line and the device can be rapidly delivered to a point on which the liquid is to be discharged. Further, the device can ejaculate the liquid per certain amount by closing the discharge-outlet opening/closing member. The above-described advantages have led to a wide use of the device.
[Patent Document 1] Japanese Patent No. 2521332